RESEARCH

Day/Night Band Radiance

The Suomi National Polar-orbiting Partnership (NPP) satellite was successfully launched on 28 October 2011. It is a bridge mission toward the Joint Polar Satellite System (JPSS), which is the US contribution to the next generation polar-orbiting operational environmental satellite system (to be coordinated with EUMETSAT). The Visible/Infrared Imager/Radiometer Suite (VIIRS) is one of five instruments onboard NPP. It builds on MODIS and AVHRR heritage, and provides high radiometric accuracy and spatial resolution multispectral imagery. For the infrared bands, Earth, Black Body, and Space View counts, and Telemetry are reported in the Raw Data Records (RDR; L1a), from which Sensor Data Records (SDR; L1b) are generated. From SDRs, a wide range of Environmental Data Records (EDRs; L2) are to be produced for ocean, land, atmosphere and cryosphere.

The first VIIRS solar reflectance images were collected on 21 November 2011. The cryoradiator doors were opened on 18 January 2012. After several days, the focal plane cooled down, and nominal quality thermal imagery was acquired. As of late April 2012, the VIIRS SDR products are being designated as "beta". This means that VIIRS SDR data are approved now for free and open distribution to users for evaluation and feedback.

SPoRT plans to routinely retrieve VIIRS SDRs from Direct Broadcast sites at the Space Science and Engineering Center at the University of Wisconsin and the Geographic Information Network of Alaska at the University of Alaska Fairbanks. There are 22 SDRs: 16 "Moderate" resolution (750 m) bands, 5 "Imagery" resolution (375 m) bands, and the low-light Day-Night-Band (750 m). Refer to Table 1 for a list of the bands. With a 3000 km swath width and nearly constant resolution from nadir to limb, VIIRS imagery will be a tremendous resource for operational forecasters. As bands allow, SPoRT will add VIIRS data to the suite of MODIS/GOES hybrid and RGB products. Table 2 lists real-time VIIRS products currently being produced by SPoRT as well as links to view imagery.